The present invention relates to material machining centers and, in particular, it relates to a material machining center wherein a vacuum-holding worktable is controllably inclinable over a zero to ninety degree angle.
A material machining center typically is comprised of a worktable orientated in a fixed horizontal position whereon the workpiece, or material to be machined, is held in place by vacuum. A typical type of machining center is known as a router such as the Model NE-2SE, manufactured by Heian Iron Works Ltd. of Hamamatsu, Japan. In order to distribute the vacuum over the surface of the table the table maay be provided with a hollow interior chamber coupled to a vacuum pump for reducing the air pressure within the chamber. Disposed in a regular array over an upper surface of the worktable are a plurality of orifices communicating with the internal vacuum chamber. A back surface of the workpiece to be machined is placed upon the upper surface of the worktable such that it overlies some number of orifices. The pressure differential existing between the upper surface of the workpiece, due to atmospheric pressure, and the back surface of the workpiece, which experiences reduced pressure, is sufficient to hold the workpiece immovable during the machining operation. In order to maintain a sufficient amount of vacuum the orifices not covered by the workpiece are typically covered by a second sheet of material known as a spoiler which is typically provided with an opening of the proper size and dimensions to accommodate the workpiece therein. As can be appreciated, this second sheet of material may be required to be stored when not in use. As may be further appreciated, the preparation and storage of such a sheet adds to the cost of the workpiece machining operation.
The actual machining operation is typically accomplished by the movements of a rotating machine tool, such as a router, in a predefined manner within an X, Y, Z coordinate system, the coordinate system being relative to the upper surface of the material.
In order to effectuate the controlled movement of the tool, a programmable controller is provided for controlling a plurality of servomotors which in turn cause the movement of the tool horizontally in an X, Y plane and, additionally, the up and down movement of the rotating tool in a Z axis.
In one such type of machining center the rotational output of the X-axis servomotor is coupled by a pair of ball screws to move a gantry assembly, upon which is movably mounted a rotating spindle holding the tool rides, along the length of the material. Movement in the Y-axis across the width of the material is accomplished by another ball screw coupled to the Y-axis servomotor which causes the movement of the tool along the gantry assembly. The up and down movement of the tool itself in the Z-axis is accomplished by the Z-axis servomotor which is also typically mounted on the gantry assembly.
A particular problem associated with such material machining centers is that an operator may experience potentially serious lower back strain when loading and unloading a sheet of material. Due to the fact that the worktable is fixed in a horizontal plane, the operator must lean over the worktable surface when handling the material. Inasmuch as a sheet of material, such as composition board, may weigh in excess of 75 pounds, a serious operator safety problem is created.
Another problem created by the horizontally disposed machining centers of the prior art is that a build-up of dust and chips may occur upon the surface of the material during the machining operation. Although such machines are typically provided with a vacuum cleaner-like dust collector to remove dust and chips, a significant portion may escape collection and remain on the worksurface, where interference with the operation of the rotating tool may occur. This problem is especially acute at high spindle rotational speeds, as is common when machining such materials as composition board and certain plastics.
A still further problem created by machining centers which have their worktable fixed in a horizontal plane is that they are not readily adaptable to operation with automated workpiece transfer systems. Such systems, which may be comprised of rolling conveyors, are typically utilized to automatically transfer a workpiece from one machining center to another, where further machining operatons are performed. Such a transfer system is especially advantageous when two or more types of tools are required to perform the desired work. Instead of requiring a tool change part way through the operation, the workpiece is instead automatically transferred to another machining center having the required tool. Thus the workpiece throughput is increased and financial savings are realized.
It is therefore an objective of the present invention to provide a machining center which may have a workpiece loaded or unloaded without unduly exposing the operator to a risk of injury.
It is a further objective of the present invention to provide a machining center which inhibits the buildup of dust and chips produced during the machining operation, thereby reducing the possibility of tool damage and other problems created by such a buildup.
It is a further objective of the present invention to provide a machining center which is more readily adaptable to integration with automatic workpiece transfer systems.
It is a further objective of the present invention to provide a machining center having a lightweight vacuum-holding worktable which is readily adaptable to holding workpieces of various sizes without requiring a spoiler sheet to maintain a sufficient vacuum and, in addition, facilitates the removal of dust and chips from the workpiece.
It is a still further objective of the present invention to provide a machining center having an inclinable worktable.